Mibefradil dihydrochloride

• CAT Number: I000599
• CAS Number: 116666-63-8
• Molecular Formula: C29H40Cl2FN3O3
• Molecular Weight: 568.55
• Purity: ≥95%
• Synonyms: [(1S,2S)-2-[2-[3-(1H-benzimidazol-2-yl)propyl-methylamino]ethyl]-6-fluoro-1-propan-2-yl-3,4-dihydro-1H-naphthalen-2-yl] 2-methoxyacetate;dihydrochloride
• InChI: InChI=1S/C29H38FN3O3.2ClH/c1-20(2)28-23-12-11-22(30)18-21(23)13-14-29(28,36-27(34)19-35-4)15-17-33(3)16-7-10-26-31-24-8-5-6-9-25(24)32-26;;/h5-6,8-9,11-12,18,20,28H,7,10,13-17,19H2,1-4H3,(H,31,32);2*1H/t28-,29-;;/m0../s1
• InChIKey: MTJLQTFHJIHXIX-GDUXWEAWSA-N
• SMILES: CC(C)C1C2=C(CCC1(CCN(C)CCCC3=NC4=CC=CC=C4N3)OC(=O)COC)C=C(C=C2)F.Cl.Cl

Mibefradil dihydrochloride (Ro 40-5967 dihydrochloride) is a calcium channel blocker with moderate selectivity for T-type Ca2+ channels (IC50s of 2.7 μM and 18.6 μM for T-type and L-type currents, respectively)[1].
Mibefradil dihydrochloride inhibits reversibly the T- and L-type currents with IC50 values of 2.7 and 18.6 μM, respectively. The inhibition of the L-type current is voltage-dependent, whereas that of the T-type current is not. Ro 40-5967 blocks T-type current already at a holding potential of -100 mV[1] At a higher concentration (20 μM), Mibefradil reduces the amplitude of excitatory junction potentials (by 37±10 %), slows the rate of repolarisation (by 44±16 %) and causes a significant membrane potential depolarisation (from 83±1 mV to 71±5 mV). At a higher Mibefradil concentration (20 μM) there is significant membrane potential depolarisation and a slowing of repolarisation. These actions of Mibefradil are consistent with K+ channel inhibition, which has been shown to occur in human myoblasts and other cells[2].
The hearing thresholds of the 24-26 week old C57BL/6J mice differ following the 4-week treatment period. The hearing threshold at 24 kHz is significantly decreased in the Mibefradil-treated and benidipine-treated groups compared with the saline-treated group (P<0.05)[3]. Compared with the saline-treated group, rats receiving Mibefradil or NSC 64013 show significant lower CaV3.2 expression in the spinal cord and DRG[4].

Reference

[1]. Mehrke G, et al. The Ca(++)-channel blocker Ro 40-5967 blocks differently T-type and L-type Ca++ channels. J Pharmacol Exp Ther. 1994 Dec;271(3):1483-8.
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[2]. Brain KL, et al. The sources and sequestration of Ca(2+) contributing to neuroeffector Ca(2+) transients in the mouse vas deferens. J Physiol. 2003 Dec 1;553(Pt 2):627-35.
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[3]. Yu YF, et al. Protection of the cochlear hair cells in adult C57BL/6J mice by T-type calcium channel blockers. Exp Ther Med. 2016 Mar;11(3):1039-1044.
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[4]. Shiue SJ, et al. Chronic intrathecal infusion of T-type calcium channel blockers attenuates CaV3.2 upregulation in nerve-ligated rats. Acta Anaesthesiol Taiwan. 2016 Oct 17. pii: S1875-4597(16)30071-6.
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